1. The sensitivity S, of a strain gauge consists of two parts: the contribution from the change in resistivity of the material and the direct contribution due to the change in shape of the strain-gauge when deformed. Show that the second part may be approximated by (1 + 2v), where v denotes the Poisson's ratio of the strain-gauge material. πTD² Hint: for a cylinder, the area is A = dA A Take the natural logarithm of each side, and the differential of each 4 Also, Poisson's ratio is v = - term to relate with respect to dD D transverse strain axial strain

A strain-gauge measurement system is mounted on an airplane wing to measure wing oscillation and strain during wind gusts. The strain system has a 90% rise time of 100 ms a ringing frequency 0f 1200 Hz and a damping ratio of 0.8. Estimate the dynamic error in measuring a 1-HZ oscillation. Also estimate any time lag. Explain in words the meaning of this information